Hi Moving_From_Gmail_For_Domains,
If you’ve already checked the “Always show from” option but still can’t see it when you create a new mail, this could be caused by the caches in the browser. I suggest you to login out from Office 365, then close the browser and clear all the caches in browser, then try it again.
In regard to the second issue you’ve concerned, It’s available to create a Inbox Rule based on the body of a message in Outlook desktop client. To do that, please try the steps below:
- Open Outlook(Mine here is Outlook 2010), in the “Move” tab in ribbon menu, click “Rules”-“Create Rules…”
- In the pop up window, click “Advanced Options…” button in the lower right, then select “With …… in the subject or body” in "step 1" in the window
- Click the link in "step 2" in the window, you can then add the filters you want in the rule
- Finish the other parts that you want to do with the Inbox rule, then click “Finish” to save the change.
You can also create a similar Inbox rule in OWA(Outlook Web App), for details, please refer to: Learn About Inbox Rules. Please feel free to post your updates here at your convenient time.